A construction machine such as a hydraulic excavator includes a boom cylinder (hydraulic cylinder) as an actuator that drives a boom or the like, and a control valve device that controls supply and discharge of working oil to and from the boom cylinder.
JP2010-242796A discloses a control valve device including a regeneration oil passage allowing communication between a bottom chamber of a boom cylinder and a rod chamber, and a boom lowering control valve that opens and closes the regeneration oil passage.
In this control valve device, working speed of the boom cylinder is increased by opening the regeneration oil passage by the boom lowering control valve, and a discharge amount of a hydraulic pump provided in a working oil pressure source is lowered, so that power of the hydraulic pump is saved.